Note: Descriptions are shown in the official language in which they were submitted.
CA 02854382 2014-06-13
CHEMICAL INJECTOR
FIELD
[001] Chemical injectors
BACKGROUND
[002] Seals are a common wear item on chemical injectors. The seals wear out
due to
chemical exposure, operating pressure and temperature. If the chemical
injector is operated at
very low pressures the seal does not work well and if at high pressure the
seals wear out too
fast. Seal failure causes a mess that needs to be cleaned up, and possibly an
environmental
pollution problem.
SUMMARY
[003] In an embodiment, a chemical injector or pump is provided that does not
have seals and
that will never leak onto soil. The pump is mounted inside a tank that
contains chemical in use,
so that if there is flow by the plunger, the chemical is still contained in
the tank.
[004] In an embodiment, there is disclosed a chemical injector, comprising a
tank, a stinger
extending into the tank, the stinger having a pump head comprising a piston
head within a
sleeve, the sleeve defining a chamber, and having an inlet check valve for one
way flow of fluid
into the chamber and an outlet check valve for one way flow of fluid out of
the chamber, the
piston head having a close tolerance liquid seal with sleeve; a drive
connected to reciprocate
the piston head in the sleeve; and outlet tubing connected to the outlet check
valve and the
outlet tubing extending out of the tank.
[005] In various embodiments, there may be included any one or more of the
following
features, in the chemical injector, the liquid seal comprises a metal alloy to
metal alloy seal, the
outlet tubing is connected into a sight glass outside of the tank, the stinger
extends downward
into the tank from an upper surface of the tank, a housing encloses the drive
for the plunger and
the outlet tubing passing through the housing, and any of the previously
mentioned features
contained within a secondary containment structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[006] There will now be described embodiments of the chemical injector with
reference to the
figures by way of example, and in which like reference characters denote like
elements, in
which:
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[007] Fig. 1 is a side elevation, broken away, showing a chemical injector,
with tank and
secondary containment;
[008] Fig. 2 is an end view of the chemical injector of Fig. 1;
[009] Fig. 3 is a perspective view of a pump with stinger and drive housing;
[0010] Fig. 4 shows a top view of an embodiment of a drive for a plunger that
reciprocates
within the stinger;
[0011] Fig. 5 shows a detail of an end of a plunger in a stinger, showing
check valves for inlet
flow and outlet flow;
[0012] Fig. 6 shows a cross-section view of an end of a plunger in a stinger,
showing check
valves for inlet flow and outlet flow; and
[0013] Fig. 7 shows an embodiment where the tank includes a secondary vessel
or pump well
attached and forming part of the tank.
DETAILED DESCRIPTION
[0014] Referring to Figs. 1 and 2, there is disclosed a chemical injector 10
comprising a tank 12
that holds chemical being injected. The tank 12 is supported by any suitable
construction such
as a frame or pads 14 within secondary containment tank 16, which itself may
sit on a skid 18. A
pump 20, shown in Figs. 1 and 3, is situated for example at the top of the
tank 12 in any
convenient location, such as the apex if the tank 12 is rounded. A stinger 22,
which forms part of
the pump 20, extends all the way to the bottom of the tank 12. The closer to
the bottom the
stinger 22 extends, the more fluid can be pumped from the tank 12, but the
stinger 22 does not
have to extend all the way to the bottom in some embodiments.
[0015] As shown in Figs. 5 and 6 in particular, the stinger 22 has a bore 24,
and within the bore
24 is a cylinder 23 that extends the length of the stinger 22. Openings 25
allow fluid from the
tank 12 to enter the bore 24 of the stinger 22, although various openings may
be used for this
purpose. The cylinder 23 terminates in a cylindrical sleeve 27 that defines a
chamber 47, and
that is provided with an inlet check valve 26 for one way flow of fluid into
the chamber 47 and an
outlet check valve 28 for one way flow of fluid out of the chamber 47. The
check valves 26, 28
are preferably located at the pump head, which is at the end of the stinger 22
furthest from the
housing 30 of the pump 20. A reciprocating plunger 32 extends from inside the
housing 30 into
the stinger 22 and terminates in a plunger head or piston 33 that in normally
operation
reciprocates within the sleeve 27. The relative sizes of the parts are shown
schematically, so
that for example the plunger or rod 32 may be made with smaller diameter than
shown in Fig. 6.
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[0016] The housing 30 houses a drive 34 for the pump 20. The drive 34 provides
the motive
force for moving the reciprocating plunger head 33 inside sleeve 27. Various
drives may be
used. In the embodiment shown, a wheel 36 rotates on an axle 38. The axle 38
has an axis A
and an eccentric portion 70 has an axis that is parallel to but off-set
laterally from axis A. A plate
71 has a central opening (not shown) that receives the eccentric portion 70
and is connected via
links 39 to plunger 32. As the axle 38 rotates, the axis of the eccentric
portion 70 rotates
around the axis A, and this eccentric motion causes links 39 and plunger 32 to
reciprocate. The
amount of movement by the plunger 32 may be made larger or smaller by change
the degree of
lateral offset of the axis of the eccentric portion 70 from the axle 38. The
wheel 36 may be
driven by a motor (not shown) that is connected by a belt (not shown) to the
wheel 36.. In
another embodiment (not shown), an oscillating rotary output of an electric
motor may be used
for the motor. In another embodiment (not shown) a continuously rotating motor
could be used,
coupled to the rod 38 so that the rod end moves in a continuous circle as in a
conventional
piston engine.
[0017] The plunger end of the injector is shown in Fig. 5. Plunger 32 moves
back and forth
inside bore 24 and the plunger head 33 reciprocates within the reinforced end
27 of cylinder 23.
. A one-way inlet valve 26 is located at the end of the injector. The area of
the stinger tube 22
that surrounds the bore 24 is filled with fluid, and the retracting motion of
the plunger head 33
inside end 27 pulls fluid within stinger tube 22 through the one-way valve 26
and the exten3ion
of the plunger head 33 pushes the fluid through outlet one-way valve 28
towards outlet tubing
52.
[0018] As seen best in cross-section in Fig. 6, the end 33 of reciprocating
plunger 32 has a
close tolerance seal 78 with sleeve 27, or more particularly with the inside
surface 40 of the
sleeve 27. The metal-to-metal seal 78 between plunger head 33 and inside
surface 40 is a close
enough seal to operate at low or very high pressures. The very small portion
of liquid that
sneaks past seal 78 serves as a thin film lubricant that maintains the
piston's ability to glide
easily along the inside surface 40 and have no effect to the wear factor.
Close tolerance liquid
seals are known within the field of engineering generally, but not, it is
thought by the inventor,
within the field of the present invention. The seal is provided by the
presence of liquid, in this
case chemical being pumped, between two solid surfaces, here the metal
interior surface 40 of
the sleeve 27 and metal components 44 of the reciprocating plunger 32.
[0019] The sleeve 27may be reinforced by for example annular metal elements 46
secured
together by rods 48 around sleeve 27. The close tolerance liquid seal also
helps allow trapped
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gases to escape the chamber 47 defined by the sleeve 27and reduce or eliminate
cavitation.
Either or both of the solid surfaces forming the seal may be any of various
hard materials such
as for example metal alloy, where the metal alloy may be tungsten carbide of
any suitable
grade, metal or ceramic or combinations of various such materials. The object
is to avoid weak
seals such as elastomeric or polymeric seals that degrade relatively rapidly
in the chemicals or
due to wear.
[0020] Outlet tubing 52 is connected to the outlet check valve 28, and the
outlet tubing extends
out of the tank 12 through the housing through loop 54 to a rate gauge 56.
Chemical pumped by
the pump 20 enters the bottom of the rate gauge 56 and exits the top. The end
58 of the outlet
tubing 52 may be connected to an injection point in for example an oil
industry vessel, tubular or
pipe (not shown). A pressure safety valve 60 may be provided on the outlet
tubing 52. A shut
off valve 62 may be provided on the end 58 of the tubing 52 to allow the rate
gauge 56 to be
isolated from the injection point, and the rate gauge 56 drained through valve
64 while air may
enter the tubing 52 through valve 63 to allow the rate gauge to drain. The
rate gauge 56 may
operate in conventional fashion by starting with the rate gauge 56 empty and
allowing it to fill
with pumping and marks on the gauge 56 along with a timer can be used to
determine how fast
the rate gauge 56 fills. The rate gauge 56 may be drained into a tray 66, and
the chemical then
returned to the tank 12. A conventional tank level gauge 68 may be provided on
the tank 12.
[0021] The stinger 20 may be inserted into any part of the tank 12, including
a manifold or
secondary vessel 21 connected to the tank 12 and such a manifold or secondary
vessel may be
considered part of the tank 12 so long as the parts are connected for free
flow of fluid from the
main part of the tank to the manifold or secondary vessel. As shown in Fig. 7,
the secondary
vessel or pump well 21 may be supported by blocks 74 and bars 76 and connected
to the main
part of the tank 12 by a flow line 78. The pump 20 operates as described in
relation to Figs. 1-6
and the outlet 80 from the pump housing 30 may be connected to rate gauge 56,
which may be
placed in any convenient location and need not be coupled to the tank 12. In
this embodiment,
the tank 12 is formed of more than one compartment.
[0022] Thus there is disclosed a reciprocating top drive system that
reciprocates a pump rod 32
that goes to the bottom of the pump stinger 22 to the bottom of the tank 12.
The pump head 50,
comprising piston head 33 and sleeve 27 is mounted at the end of the stinger
22 and is
submerged in fluids in the tank 12. The pump head 50 is for example carbide
piston and sleeve
27 with a very tight machined tolerance that allows the piston head 33 to pump
up and down
and glide in a film of the chemical that is slipping by the tolerance.
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[0023] The tolerance will only let a very small portion of the liquids to
sneak by the piston 33
and that thin film lubricates the piston 33 evenly all around the cylinder 27.
This pump, made
with conventional materials used for oil servicing tools, can operate at low
pressures or high
pressures up to 5000PSI with low wear.
[0024] This is believed by the inventor to be a huge breakthrough in well site
chemical pumps to
reduce spills and maintenance costs over the years. Also it prevents or at
least reduces
environmental problems from chemical getting into soil.
[0025] The pump is a vertical top drive assembly reciprocating a pump rod 32
up and down in
the stinger tube 22. The stinger tube 22 is easily removed by flipping the top
drive back and
pulling the stinger tube out to maintain check valves or pump head parts.
[0026] A secondarily contained bulk tank preferably houses all the fittings
and sight glasses so
that there is no chance of loose connections or broken sight glasses to worry
about leaking into
soil.
[0027] Everything is preferably secondarily contained and will rarely leak.
[0028] A high pressure rate gauge 56 may be used to set the chemical injection
rate per day. As
the fluid discharges the pump, it passes through a visible high pressure sight
glass and it gives
precise injection rates as per field conditions, field conditions consist of
exact line pressures,
chemical viscosity, chemical temperature and pump power input RPM. All of
these conditions
can change your pump rate so it is best to set every pump to field conditions.
[0029] The tank level gauge 68 and the high pressure rate gauge 56 are
preferably mounted
inside the tank secondary containment area 16 so that all gauges and fittings
are inside the
secondary containment area 16. The pump goes in the chemicals tank 12, and is
sealless.
Previous pumps known to the inventor had Teflon seals, which wore out. This
pump may run at
high pressure for example 6000psi. The pump outlet goes through a rate gauge
or like device to
check how much is being injected.
[0030] The submersible design that allows a machined piston and cylinder to be
used without a
Teflon seal is a big advancement since the liquid slip lubricates and allows
any small air bubbles
to be pushed out of the piston. This design reduces or eliminates any air
locks that will not let
the pump prime and pump correctly. The slip fluid keeps the piston washed
clean.
[0031] The high pressure sight glass makes it possible to meter the exact
amount of chemical
needed daily to cut chemical waist and cost.
[0032] Immaterial variations in the disclosed embodiments may be made without
departing from
the claims.
